WAN speed drops significantly when downloading large 10+ GB files!?

[Herman]

Hi everybody,

Using pfSense for 3 weeks now. Thanks to you guys I am finding my way through the interface. From what I have experienced pfSense is an outstanding firewall.

Now to the question. My WAN speed is a 400/40 cable connection. PfSense is running as a Hyper-V virtual machine. The VM has one virtual LAN network card and of course a virtual WAN network card. The physical network card is an Intel(R) Ethernet Server Adapter I350-T4. The Hyper-V role is running on a Windows Server 2016 environment. So far so good. So far I know everything is working well.

I also download large files from UseNet pay servers. When I do so suddenly the WAN speed drops from approximately 50MB to a very inconsistent speed between 0 MB and 40 MB. Note the picture below to see the problem visualized.

What can be the cause of this issue? Somebody having thoughts how to solve this and get a stable fast download speed?

Appreciate your help,

Regards,
Herman